The invention relates to a liquid cooled internal combustion engine with an engine block including a cooling water space and a cylinder head mounted on the engine block by cylinder head bolts with a gasket disposed therebetween. The cylinder head includes a cooling water chamber delimited by cylinder head top, bottom, and side walls and for each cylinder intake passages leading to one of the side walls and exhaust passages leading to the opposite side wall. For each cylinder, the cylinderhead has a domed area for receiving a spark plug or a fuel injector, and various openings by way of which the cooling water chamber of the cylinder head is in communication with the cooling water space in the engine block.
In internal combustion engines of this type (see for example, DE AS 1526 328), the cylinder head bolts extend through passages in bolt columns, which are arranged between the cylinder head top wall and the cylinder head bottom wall. They guide the bolts and form a support structure between the cylinder head bottom and the cylinder head top wall to increase the rigidity of the cylinder head. However, after startup of the internal combustion engine, the cylinder head and the engine block heat up substantially faster than the cylinder head bolts. The cylinder head and the engine block are relatively rapidly heated by the cooling water whereas the usually very long cylinder head bolts are heated up only by heat conduction via their contact areas with the cylinder head and via the threaded ends. This leads to a time hysteresis in the temperature curve between the bolts and the surrounding components which results, with the already stretched cylinder head bolts, in a reduction of the bolt forces after repeated startup of the engine. Also, the bolt guide columns form obstacles to the water flow through the cylinder head.
It is the object of the present invention to provide for a more rapid heating of the cylinder head bolts by which the cylinder head is mounted onto the engine block so that any bolt force change is reversible.